BEPCⅡ束团缺口信号的提取

 基于隧道二极管单稳态电路、高速可重触发电路、ECL技术等多种高速电路技术设计了BEPCⅡ束团缺口信号提取电路。介绍了BEPCⅡ储存环中带缺口的多束团运行模式。对Pickup电极感应信号经过长电缆传输衰减后的波形进行了研究。分析了缺口提取电路中处理快速信号的隧道二极管单稳态电路原理,该电路可以将0.3 ns的正脉冲展宽到4 ns的ECL电平脉冲。给出了标准束团注入和非标准注入情况下束团缺口判定逻辑。测试结果表明:此电路对各种束团注入情况均能正常工作,且提取出的同步信号均方根抖动值仅为80.49 ps,满足设计要求。     

基于单相交错式并联PFC的Saber仿真应用研究

传统的Boost APFC在中大功率（≥3 kW）应用时有显著的开关损耗和整流器的反向恢复损耗,而且需要较大的输入电感电容,使得其成本和效率明显降低。针对这些问题采用新型交错式PFC控制后其不仅具有低功耗、低EMI、高效率,而且还可以进一步扩展功率等级范围。文中创新性地运用Synospsys公司强大的数模混合仿真软件Saber对一款大于3 kW的交错式并联PFC系统进行了DC分析、瞬态分析、参数扫描分析以及FFT分析,仿真分析结果验证了交错式并联PFC不仅具有减小输入输出电流纹波、减小电感电容值和提高变换器效率和功率等级等优点,而且有利于缩短开发周期、降低设计成本及便于软件的工程调试。     

基于SP4T开关的4位MEMS开关线式移相器设计

设计了一款4位MEMS开关线式移相器,由SP4TMEMS开关和微带传输线构成,工作于X波段。单刀四掷(single pole 4throw,SP4T)开关用于切换两条不同电长度的信号通道,即参考相位通道和延迟相位通道。每个SP4T开关包含4个悬臂梁接触式RF MEMS串联开关。介绍了4位MEMS开关线式移相器的总体设计,并给出了其关键部件SP4T开关和相位延迟线的设计细节。采用ADS软件仿真分析了器件的电气性能。仿真分析得到:SP4T开关在中心频率10GHz处的回波损耗为-36dB,插入损耗约为0.18dB;移相器各相位的回波损耗均低于-15dB,插入损耗为-0.8～-0.4dB。这种射频MEMS移相器具有小型化、低功耗和高隔离度的优点。     

倒立摆系统的状态空间极点配置控制设计

为实现多输人多输出、高度非线性、不稳定的倒立摆系统平衡稳定控制,将倒立摆系统的非线性模型进行近似线性化处理,获得系统在平衡点附近的线性化模型.利用牛顿一欧拉方法建立直线型一级倒立摆系统的数学模型.在分析的基础上,基于状态反馈控制中极点配置法对直线型一级倒立摆系统设计控制器.由MAT-LAB仿真及对实际系统的调试验证,表明采用的控制策略是有效的,设计的控制器对直线型一级倒立摆系统的平衡稳定控制效果好,提高了系统的抗干扰能力.     

Scattering by a Cylindrical Trap in the Critical Case

We study a two-dimensional analog of the Helmholtz resonator with walls of finite thickness in the critical case, for which there exists a frequency which is simultaneously the limit of poles generated both by the bounded component of the resonator and by a narrow communication channel. Under the assumption that the limit frequency is a simple frequency for the bounded component, by using the method of matched asymptotic expansions, we construct asymptotics for the two sequences of poles converging to this frequency. We obtain explicit formulas for the leading terms of the asymptotics of poles and for the solution of the scattering problem.     

A semidefinite optimization approach to the steady-state analysis of queueing systems

Obtaining (tail) probabilities from a transform function is an important topic in queueing theory. To obtain these probabilities in discrete-time queueing systems, we have to invert probability generating functions, since most important distributions in discrete-time queueing systems can be determined in the form of probability generating functions. In this paper, we calculate the tail probabilities of two particular random variables in discrete-time priority queueing systems, by means of the dominant singularity approximation. We show that obtaining these tail probabilities can be a complex task, and that the obtained tail probabilities are not necessarily exponential (as in most ‘traditional’ queueing systems). Further, we show the impact and significance of the various system parameters on the type of tail behavior. Finally, we compare our approximation results with simulations.     

提高PFC性能的策略综述

PFC的性能是影响其应用的重要原因，根据近年来的发展介绍了常用的提高PFC性能的策略，并用功率流理论对这些方法的效率及特点进行了比较分析，说明了各种方案的优缺点。     

气密性高Bs合金及其在微波管中的应用

本文简要介绍了新型气密性高饱和磁感应（Ｂｓ）合金的主要特点及其在真空微波管中的应用。     

Analysis and optimal realization of pole-zero sensitivity for FIR digital filters

Aiming at the deviation of pole and zero in filters which caused by the finite word length (FWL) effects,the sensitivity of pole and zero for FIR digital filters to coefficient errors was studied based on the state-space model.Unlike the IIR filter,the system matrix in state-space model of the FIR filter was defective.A set of generalized eigenvectors of defective matrix was introduced to analyze the pole sensitivity and derive the measure expression,and optimal realizations with respect to pole-zero sensitivity for FIR filters were proposed by finding optimal transformation matrices according to the similarity transformation theory.Theoretical analysis and simulation experiments show that the poles of a FIR filter are more sensitive to coefficient errors,and the proposed optimal realizations can reduce the sensitivity.     

Optimization Design of Holding Poles Based on the Response Surface Methodology and the Improved Arithmetic Optimization Algorithm北大核心CSCD

抱杆优化设计需要耗费大量有限元分析计算时间,难以确定可行域.该文采用响应面法(response surface method,RSM)来模拟抱杆结构的真实响应,提出了改进的算术优化算法(improved arithmetic optimization algorithm,IAOA)对抱杆结构进行优化设计.将分数阶积分引入算术优化算法(arithmetic optimization algorithm,AOA),改善了算法的开发能力.采用拉丁超立方抽样,选取抱杆结构杆件截面试验样本,利用最小二乘法对样本点进行分析,构建了抱杆结构应力和位移关于杆件截面尺寸的二阶响应面代理模型.建立以抱杆质量最小化为优化目标,许用应力和位移为约束条件的优化模型,采用IAOA对其进行求解.结果表明:二阶响应面模型能够准确预测抱杆结构的响应值,IAOA的求解精度得到显著提升,代理模型可大幅降低有限元分析所需的计算代价,优化后抱杆结构质量减轻了8.2%.联合使用RSM和IAOA可有效求解大型空间杆系结构的优化设计问题.